This invention relates to a temperature differential detection device and more particularly to a device and technique for detecting hot spots in heavy wall vessels and containers.
In the utilization of heavy wall vessels at elevated temperatures and pressures, it is desirable to monitor the temperature of the vessel wall for the occurrence of "hot spots". For example, in the solvent refined coal process (SRC-I) for direct coal liquefaction such as generally referred to in U.S. Pat. No. 4,272,501 and U.S. Pat. No. 4,397,732, the detection of the existence of hot spots in the walls of various process vessels, such as dissolvers or reactors, is necessary. The existence of hot spots in the walls of such process vessels can produce undesirable and detrimental coking. Accurate and reliable detection of such hot spots permits timely corrective procedures to prevent such undesirable coking. Furthermore, in the "second-stage" hydrocracking of SRC-I liquified and deashed product streams, the existence of hot spots in the wall of the catalytic reactor (i.e., expanded-bed hydrocracker) can indicate the possibility of wall failure.
Since many of the process steps in the solid refined coal process are accomplished at elevated pressures, it is also desirable to minimize any penetration of the reaction vessel wall and, accordingly, it is advantageous to be able to detect hot spots without the necessity for vessel wall penetration.
Accordingly, it is an object of the present invention to provide a new and improved temperature differential detection device for accurately detecting hot spots in a vessel or container wall without penetration thereof.
Another object of the invention is to provide a temperature differential detection device for accurately detecting a temperature differential between predetermined wall portions of a vessel or container wall.
A further object of the invention is to provide a temperature differential detection device that detects average temperature over an extended circumferential path of a container wall.
A still further object of the invention is to provide a temperature differential detection device which is durable and long lasting in use and is economical to manufacture.